The present invention is directed to devices for monitoring automated machine tools, and in particular, automated machines which perform work using a reciprocating appliance.
Automated machine tools are used to perform various tasks upon metal, and in particular sheet metal and are in wide use today. Specific types of automated machine tools are those which reciprocally drive an appliance against successive work pieces to perform various tasks, e.g. cutting, drilling or punching the work piece.
Even though these types of machines are automated it is still necessary to monitor the progress of the work performed by each machine during the entire production run. Examples of presently available devices for monitoring automated machines are disclosed in U.S. Pat. Nos. 3,339,434, issued to Sparling; 3,440,848, issued to Zeitlin et al; 3,836,834, issued to Abbatiello et al; and 3,979,980 issued to Biester et al.
Generally presently available devices monitor the force being applied by the machine appliance to the work piece. These types of monitoring devices measure the amount of applied force to ensure that while a sufficient amount is being applied to perform the desired operation the applied amount will not exceed that amount which would cause damage to the work piece.
However, even when the force being applied is sufficient to carry out the intended operation there remains other variables which may effect the quality of the product being produced during the operation of the automated machine tool. For example, the physical dimensions of work pieces will vary from piece to piece. During the operation of an automated machine tool it is necessary to determine whether the piece upon which the work is being performed is within a suitable tolerance range. That is, each work piece needs to be evaluated in order to ensure that it possesses a proper thickness or hardness to ensure the suitability of the formed product. If such work piece does not possess a suitable dimension then the resulting product will not be useful for its intended purpose, or will be of such poor quality that it will have a shortened life expectancy.
Another parameter which is important to the functioning of the machine tool is the condition of the appliance being used, for example the condition of a stamp or punch. During the operation of the automated machine tool the appliance will experience wear. As the appliance continues to wear it will either fail to provide a clean cut through the work piece, or become subject to breakage. A worn appliance will increasingly roll or push the metal of the work piece aside instead of providing a clean cut, which will result in an unacceptable product that will have to be discarded. If the appliance is damaged because of severe wear then the reulting work pieces will also be damaged and unacceptable.
It is thus desirable to monitor not only the force being applied by the appliance, but also measure the tolerance of the work piece and the condition of the appliance during the course of operating a machine tool.